On Tuesday, 26 October 1999 at 11:26:47 +0100, Geoff Buckingham wrote:
> On Sun, Oct 24, 1999 at 09:58:11AM -0600, Greg Lehey wrote:
>>
>> Indeed. It's quite easy to put all cylinder groups on a single
>> spindle; I've seen reports of up to 80% degradation under these
>> circumstances.
>>
>>> Where sequential read/write performance is not critical you can stripe at
>>> cluster size to avoid this. Other wise using an odd number of spindles for
>>> a stripe and an even number for a RAID3 or RAID5 or stripeing at an interval
>>> which is not a power of two should work (12,24,48,76 etc)
>>
>> The best I've heard of is 768 kB - 1 sector. This works on Vinum, but
>> it seems that most RAID controllers use a somewhat simplistic striping
>> algorithm. You might like to try 31 kB or such. This won't make any
>> difference with rawio, though.
>
> I would agree from experiance that 768 KB seems a good selection for vinum
> and probably ccd too
There's a big difference between 768 kB and 767½ kB. That's the point
I was trying to make. With 768 kB, you risk having all your
superblocks on one drive.
Greg
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